Apparatus for treatment of ischemic heart disease by providing transvenous myocardial perfusion

ABSTRACT

Apparatus and methods are provided for use in open surgical and transluminal methods for supplying long-term retrograde perfusion of the myocardium via a conduit disposed between the left ventricle and the coronary sinus. In a first method, an opening is formed between the left ventricle and the coronary sinus, and the coronary ostium is partially occluded using a stent that prevents the pressure in the coronary sinus from exceeding a predetermined value. In an alternative method, a first end of a conduit is inserted transeptally through the right atrium and obliquely into the posterior septal endocardium of the left ventricle via the posterior pyramidal space, while a second end of the conduit is inserted into the coronary sinus via the coronary ostium. A pressure-limiting valve is included in the conduit. In either method, the outlet from the left ventricle to the coronary sinus may include a one-way valve to prevent backflow from the coronary sinus into the left ventricle during cardiac diastole.

This application is a division of U.S. Pat. No. 08/714,466, filed Sep.16, 1996 now U.S. Pat. No. 5,655,548, entilted METHOD AND APPARATUS FORTREATMENT OF ISCHEMIC HEART DISEASE BY PROVIDING TRANSVENOUS MYOCARDIALPERFUSION.

FIELD OF THE INVENTION

The present invention relates generally to treatment of ischemic heartdisease, and more particularly, cases involving diffuse coronaryatherosclerosis, by perfusing the myocardium with oxygenated blood fromthe left ventricle using the venous system of the heart.

BACKGROUND OF THE INVENTION

The cardiac blood perfusion system is composed of two coronary arterialvessels, the left and right coronary arteries, which perfuse themyocardium from the epicardial surface inward towards the endocardium.Blood flows through the capillary systems into the coronary veins, andinto the right atrium via the coronary sinus. Two additional systems,the lymphatic and the Thebesian veins, drain a portion of the bloodperfused into the myocardium directly into the heart chambers. Thevenous system has extensive collaterals and, unlike the coronaryarteries, does not occlude in atherosclerotic disease.

A number of techniques have been developed to treat ischemic heartdisease caused, for example, by atherosclerosis. These treatments haveimproved the lives of millions of patients worldwide, yet for certainclasses of patients current technology offers little hope or relief.

Best known of the current techniques is coronary artery bypass grafting,wherein a thoracotomy is performed to expose the patient's heart, andone or more coronary arteries are replaced with synthetic grafts. Inpreparation for the bypass grafting, the heart is arrested using asuitable cardioplegia solution, while the patient is placed oncardiopulmonary bypass (i.e., a heart-lung machine) to maintaincirculation throughout the body during the operation. Typically, a stateof hypothermia is induced in the heart muscle during the bypassoperation to reduce oxygen utilization, thereby preserving the tissuefrom further necrosis. Alternatively, the heart may be perfusedthroughout the operation using either normal or retrograde flow throughthe coronary sinus, with or without hypothermia. Once the bypass graftsare implanted, the heart is resuscitated, and the patient is removedfrom cardiopulmonary bypass.

Drawbacks of conventional open heart surgery are that such surgery istime-consuming and costly, involves a significant risk of mortality,requires a lengthy period of recuperation, and involves significantdiscomfort to the patient.

As a result of the foregoing drawbacks, techniques have been developedthat permit coronary bypass grafting to be performed endoscopically,i.e., using elongated instruments inserted through incisions locatedbetween the ribs. A drawback of these keyhole techniques, however, isthat they can be used only for coronary arteries that are readilyaccessible, and not, for example, those located posteriorly.

Alternatively, techniques such as percutaneous transluminal angioplasty("PTA") have been developed for reopening arteries, such as the coronaryarteries, that have become constricted by plaque. In these techniques, aballoon catheter is typically inserted into the stenosis and theninflated to compress and crack the plaque lining the vessel, therebyrestoring patency to the vessel. Additionally, a vascular prosthesis,commonly referred to as a "stent," may be inserted transluminally andexpanded within the vessel after the angioplasty procedure, to maintainthe patency of the vessel after the PTA procedure.

U.S. Pat. No. 5,409,019 to Wilk describes an alternative method ofcreating a coronary bypass, wherein a valve-like stent is implantedwithin an opening formed between a coronary artery and the leftventricle. The patent describes that the stent may be implantedtransluminally.

A drawback of the foregoing transluminal approaches is that thetreatment device, e.g., the balloon catheter or the stent deliverysystem described in U.S. Pat. No. 5,409,019, must be inserted in thevessel before it can be expanded. Occasionally, a stenosis may occludeso much of a vessel that there is insufficient clearance to advance aguidewire and catheter within the stenosis to permit treatment. Inaddition, arterial blockages treatable using PTA techniques arerestricted to the portions of the anatomy where such techniques can bebeneficially employed.

Moreover, the above-described techniques--both open-surgery andtransluminal--are useful only where the stenosis is localized, so thatthe bypass graft or PTA procedure, when completed, will restore nearnormal blood flow to the effected areas. For certain conditions,however, such as diffuse atherosclerosis, blockages may exist throughoutmuch of the coronary artery system. In such situations, treatment, ifpossible, typically involves heart transplant.

Historically, attempts have been made to treat diffuse blockages of thecoronary arterial system by introducing retrograde flow through thecoronary venous system. As described,. for example, in W. Mohl,"Coronary Sinus Interventions: From Concept to Clinics," J. CardiacSurg., Vol. 2, pp. 467-493 (1987), coronary venous bypass grafts havebeen attempted wherein the coronary sinus was ligated, and a shunt wasimplanted between a cardiac vein and the aorta, thus providing permanentretrograde perfusion. It was observed that such bypass grafts resultedin underperfusion of certain regions of the myocardium and edema of thevenous system. Consequently, as reported in the aforementioned Mohlarticle, these techniques are rarely used in cardiac surgery, whilepermanent retroperfusion is never used in interventional cardiology.

Despite disenchantment with retroperfusion via the coronary sinus forlong-term perfusion of the myocardium, retrograde coronary venousperfusion is now routinely used in coronary interventional procedures toperfuse the heart during the procedure. Franz et al., in "TransfemoralBalloon Occlusion of the Coronary Sinus in Patients with AnginaPectoris,"Radiologia Diagnostica, 31(1), pp. 35-41 (1990), demonstratedthe possibility of transfemoral coronary sinus balloon occlusion inpatients with angina pectoris. In recent years, the use of retrogradearterial perfusion of blood through the coronary sinus has gained wideacceptance as a technique to preserve the myocardium during bypassprocedures (Kuraoka et al., "Antegrade or Retrograde Blood CardioplegicMethod: Comparison of Post-Surgical Right Ventricular Function andConduction Disturbances," Japanese J. Thoracic Surg., 48(5), pp. 383-6,(1995)) and during high risk or complicated angioplasty (Lincoff et al.,"Percutaneous Support Devices for High Risk or Complicated CoronaryAngioplasty," J. Am. Coll. Cardiol., 17(3), pp. 770-780 (1991)). Thisperfusion technique allows continuous warm cardioplegia and allows theflow of blood through the coronary venous bed distal to the occlusion.

It has also been reported by Rudis et al. in "Coronary Sinus OstialOcclusion During Retrograde Delivery of Cardioplegic SolutionSignificantly Improves Cardioplegic Distribution and Efficiency," J.Thoracic & Cardiovasc. Surg., 109(5), pp. 941-946 (1995), thatretrograde blood flow through the coronary venous system may beaugmented by coronary ostial occlusion. In this case, blood flowsretrograde to the myocardium and drainage is through the lymphaticsystem and the Thebesian veins. Huang et al., in "Coronary SinusPressure and Arterial Venting Do Not Affect Retrograde CardioplegicDistribution," Annals Thoracic Surg., 58(5), pp. 1499-1504, that flowthrough the myocardium is not significantly effected by coronaryarterial occlusion and venting, or by increases in coronary perfusionpressure. Also, K. Ihnken et al., in "Simultaneous Arterial and CoronarySinus Cardioplegic Perfusion, an Experimental and Clinical Study,"Thoracic and Cardiovascular Surgeon, Vol. 42, pp. 141-147 (June 1994),demonstrated the benefits of using simultaneous arterial and coronarysinus perfusion during cardiac bypass surgery, with no ventricularedema, lactate production, lipid peroxidation, or effect on post-bypassleft ventricular elastance or stroke work index.

For a large number of patients in the later phases of ischemic heartdisease, and particularly diffuse atherosclerotic disease, currenttechnology offers little relief or hope. In such instances, humanelyextending the patient's life for additional months may providesignificant physical and emotional benefits for the patient.

In view of the foregoing, it would be desirable to provide methods andapparatus for use in treating ischemic heart disease in a wider range ofopen surgical and interventional cardiology procedures.

It also would be desirable to provide methods and apparatus forproviding transvenous myocardial perfusion that reduce the risk of edemawithin the venous system.

It would further be desirable to provide methods and apparatus thatenable patients suffering from the later phases of diffuse ischemicheart disease to experience renewed vigor, reduced pain and improvedemotional well-being during the final months or years of their lives.

SUMMARY OF THE INVENTION

In view of the foregoing, it is an object of this invention to providemethods and apparatus for use in treating ischemic heart disease in awider range of open surgical and interventional cardiology procedures.

It is another object of the present invention to provide methods andapparatus for providing transvenous myocardial perfusion that reduce therisk of edema within the venous system.

It is a further object of this invention to provide methods andapparatus that enable patients suffering from the later phases ofdiffuse ischemic heart disease to experience renewed vigor, reduced painand improved emotional well-being during the final months or years oftheir lives.

In accordance with the present invention, open surgical and transluminalmethods are provided for supplying long-term retrograde perfusion of themyocardium via a conduit disposed between the left ventricle and thecoronary sinus.

In a first method performed in accordance with the present invention,apparatus for forming an opening between the coronary sinus and the leftventricle is advanced into the coronary sinus through the coronaryostium (located in right atrium). Access to the right atrium may beestablished using either the subclavian veins and the superior vena cavaor an approach through a femoral vein. Once an opening is formed betweenthe left ventricle and the coronary sinus, the coronary ostium ispartially occluded using a stent that prevents pressure in the coronarysinus from exceeding a predetermined value, generally, about 60 mm Hg.Optionally, a valved stent may be disposed in the passageway between theleft ventricle and the coronary sinus to maintain the patency of theopening during cardiac systole and to prevent flow from the coronarysinus into the left ventricle during cardiac diastole.

In an alternative method of the present invention, suitable for useeither as an open surgical procedure or as a transluminal procedure, afirst end of a conduit is inserted transeptally through the right atriumand obliquely into the posterior septal endocardium of the leftventricle via the posterior pyramidal space, while a second end of theconduit is inserted into the coronary sinus via the coronary ostium inthe right atrium. As in the first method, the conduit may include meansfor maintaining pressure in the conduit and coronary sinus below apredetermined value, and may include a one-way valve preventing backflowfrom the coronary sinus to the left ventricle during cardiac diastole.

Further features of the invention, its nature and various advantageswill be more apparent from the accompanying drawings and the followingdetailed description of the preferred embodiments.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a partial perspective view of a human heart illustrating thecoronary arteries;

FIG. 2 is a partial perspective view of a human heart illustrating thecardiac veins;

FIG. 3 is a sectional view of the myocardium, showing certain componentsof the cardiac venous system;

FIG. 4 is a sectional view of a human heart showing the placement ofapparatus of the present invention in accordance with a first method ofthe present invention;

FIG. 5 is a sectional view of a plug constructed in accordance with theprinciples of the present invention for partially occluding the coronaryostium;

FIG. 6 is a sectional view of a stent constructed in accordance with theprinciples of the present invention for forming a conduit between theleft ventricle and the coronary sinus, illustratively including aone-way valve;

FIG. 7 is a sectional view of the distal end of a catheter systemconstructed in accordance with the principles of the present inventionfor delivering the plug and stent of FIGS. 5 and 6;

FIGS. 8A, 8B, 8D and 8E are sectional views of a human heartillustrating the steps of transluminally creating a venous bypass inaccordance with the principles of the present invention, while FIG. 8Cis a cross-sectional view of a catheter suitable for use with a cuttinginstrument for forming a passageway from the coronary sinus to the leftventricle.

FIG. 9 is a sectional view of a human heart showing the placement ofalternative apparatus of the present invention in accordance with analternative method of the present invention;

FIG. 10 is a sectional view of alternative apparatus constructed inaccordance with the principles of the present invention for forming aconduit between the left ventricle and the coronary sinus,illustratively including a one-way valve adjacent the inlet from theleft ventricle;

FIGS. 11A and 11B are, respectively, an illustrative sectional view ofapparatus for implanting a first end of the conduit constructed inaccordance with the present invention, and a perspective view of a stepof transluminally implanting the apparatus of FIG. 10; and

FIG. 12 is a partial perspective of a catheter for implanting a secondend of the conduit of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

The present invention relates generally to methods and apparatus forproviding transvenous myocardial perfusion for patients suffering fromdiffuse forms of ischemic heart disease, such as atherosclerosis. Inaccordance with the methods of the present invention, a conduit isformed between the left ventricle and the coronary sinus, so that bloodejected from the left ventricle enters the coronary sinus during cardiacsystole. The apparatus of the present invention includes means forlimiting peak pressure in the coronary sinus during cardiac systole to avalue less than that believed to result in edema of the venous system,generally, about 60 mm Hg.

Referring to FIGS. 1 to 3, the coronary arterial and venous systems ofthe human heart are described. As shown in FIG. 1, the myocardium of ahealthy human heart is nourished by left coronary artery 20, includingcircumflex branch 21 and anterior descending branch 22, and rightcoronary artery 23, including descending posterior branch 24 andmarginal branch 25. Left and right coronary arteries 20 and 23 emanatefrom the aorta (not shown) slightly above aortic semilunar valve 26.During cardiac bypass surgery, it is common for occluded sections of theleft and right coronary arteries 20 and 23 to be excised and replacedwith synthetic grafts.

FIGS. 2 and 3 illustrate the cardiac venous system of the human heartand a model of the myocardial veins, respectively. The venous systemcomprises coronary sinus 30 that provides drainage for great cardiacvein 31, middle cardiac vein 32, and small cardiac vein 33. Deoxygenatedblood flowing into coronary sinus 30 exits via coronary ostium 34 intothe right atrium. The venous system further includes anterior cardiacveins 35 that drain directly into the right atrium.

With respect to FIG. 3, myocardium 40 includes a lattice of capillaries41 that drain deoxygenated blood into intramyocardial veins 42. Frommyocardial veins 42, a fraction of the blood drains into the cardiacveins via subepicardial veins 43, while the remainder drains through theThebesian veins 44 directly into the atrial and ventricular cavities. Ithas been reported in healthy human hearts that approximately 70% of thedeoxygenated blood is drained through the coronary sinus, while theremaining 30% is drained in about equal proportions into the left andright atria and ventricles via the lymphatic system and the Thebesianveins. It has likewise been reported that when individual components ofthe venous system (i.e., the coronary sinus, lymphatic system andThebesian veins) are occluded, the flow redistributes itself through theremaining unoccluded channels.

The coronary arteries are formed of resilient tissue fibers thatwithstand the peak pressures typically generated in the left ventricleduring cardiac systole, generally up to about 120 mm Hg. By contrast,the tissue fibers of the cardiac veins are much less resilient thanthose of the coronary arterial system, with peak pressures in thecoronary sinus generally in a range of 6-10 mm Hg. Consequently, asreported for example in the aforementioned Mohl article, adequatedrainage of deoxygenated blood can be provided by the lymphatic systemand the Thebesian veins even when the coronary sinus is totallyoccluded. However, as also reported in that article, long-termretroperfusion via the coronary sinus often leads to edema of thecardiac veins, which are generally believed to be incapable ofsustaining long-term pressures above about 60 mm Hg. The methods andapparatus of the present invention are intended to address thissignificant drawback of long-term retroperfusion via the coronary sinus.

Referring now to FIG. 4, a first embodiment of the method and apparatusin accordance with the present invention is described. FIG. 4 depictshuman heart 50 in cross-section, within which apparatus of the presentinvention has been implanted in accordance with the methods of thepresent invention. Human heart 50 includes superior vena cava 51 andinferior vena cava 52 communicating with right atrium 53, rightventricle 54, left atrium 55, left ventricle 56, and aorta 57 (forclarity, the pulmonary artery has been omitted). Tricuspid valve 58separates right atrium 53 from right ventricle 54, while mitral valve 59separates left atrium 55 from left ventricle 56. Aortic semilunar valve60 separates left ventricle 56 from aorta 57. Coronary sinus 61 is shownin dotted outline passing behind heart 50 and exiting into right atrium53 at coronary ostium 62.

In accordance with a first method of the present invention, plug 70 islodged in coronary ostium 62, while stent 71 is disposed in passageway72 created between coronary sinus 61 and left ventricle 56. Plug 70,shown in greater detail in FIG. 5, preferably comprises a resilientbiocompatible material, e.g., silicon or soft plastic, which is formedinto a slightly tapered tubular member 75. Tubular member 75 includesbore 76 and pressure sensitive valve 77 disposed in bore 76. Tubularmember 75 further includes proximal flange 78 that abuts against theright atrial endocardium and a plurality of resilient barbs or ribs 79that engage the interior wall of the coronary sinus when plug 70 isdisposed in the coronary sinus through coronary ostium 62, therebysecuring plug 70 in position. Plug 70 also may include radiopaque markerrings 74, e.g., gold hoops, embedded in the thickness of tubular member75 for determining the location and orientation of plug 70 underfluoroscopic imaging.

Pressure sensitive valve 77 is designed to remain closed until thepressure in the coronary sinus reaches about 60 mm Hg. Once the coronarysinus pressure reaches about 60 mm Hg, valve 77 opens to vent anyadditional blood ejected into the coronary sinus via passageway 72 andstent 71 into right atrium 53. Pressure sensitive valve 77 may beconstructed employing knowledge per se known in the art for constructionof synthetic valves such as the mitral, aortic, and pulmonary valves.

Stent 71, shown in greater detail in FIG. 6, is preferably similar indesign to plug 70, and includes a tubular member 80 having proximalflange 81, bore 82 and resilient barbs or ribs 83 disposed around itscircumference. Stent 71 preferably comprises a compliant materialcapable of bending along its length, such as silicon or a resilientplastic, thus permitting the stent to be transported transluminallythrough tortuous passages. Stent 71 also may have embedded withintubular member 80 circumferential hoops 85 formed of a relatively rigidmaterial, e.g., stainless steel. Hoops 85, if provided, enable the stentto resist radial compression, thereby enabling stent 71 to maintain thepatency of bore 82 against contraction of the left ventricularmyocardium during cardiac systole. Stent 71 optionally may includeone-way valve 84 that prevents blood from being drawn from the coronarysinus into the left ventricle during cardiac diastole. Certain of hoops85 also may be coated with a radiopaque material visible underfluoroscopic imaging.

Proximal flange 81 abuts against the interior wall of the coronary sinuswhen stent 71 is implanted in passageway 72 formed between the coronarysinus and the myocardium of the left ventricle. When stent 71 ispositioned in passageway 72 as shown in FIG. 4, barbs or ribs 83 securestent 71 from withdrawing into the coronary sinus, while proximal flange81 prevents the stent from being drawn into the left ventricle.

Plug 70 and stent 71 are transported to, and implanted within, thecoronary sinus using flexible catheter 90, the distal end of which isshown in FIG. 7. In one embodiment of the present invention, catheter 90includes exterior sheath 91, pusher member 92 disposed to reciprocatewithin exterior sheath 92 and spool 93 affixed to the distal end ofpusher member 92. Pusher member 92 and spool 93 include central bores 94and 95, respectively, through which guidewire 96 slidably extends. Thedistal end of spool 93 includes step 97 that is dimensioned to looselyengage bore 82 of stent 71 (as well as bore 76 of plug 70). Stent 71 isloaded into the distal end of catheter 90 within exterior sheath 91 sothat flange 81 of the stent is flexibly bent longitudinally betweenspool 93 and exterior sheath 91, and step 97 engages the proximal end ofbore 82. Guidewire 96 extends through one-way valve 84 (if provided).

Implantation of apparatus 70 in accordance with a first method of thepresent invention is now described with respect to FIGS. 8A through 8E.In FIG. 8A, catheter 100 is advanced along guidewire 101 through theaxillary and subclavian veins (not shown) and into right atrium 53 viasuperior vena cava 51. Catheter 100 is then advanced through coronaryostium 62 and into coronary sinus 61. Catheter 100 preferably includespiezoelectric ultrasound elements for mapping the coronary sinus, theleft ventricular myocardium, and the anatomy of the left ventricle.

Once the cardiologist has mapped these features of the heart, catheter100 is withdrawn (guidewire 101 is left in place) and catheter 105 isadvanced along guidewire and into the coronary sinus. The distal end ofcatheter 105 is illustrated in FIG. 8C as including lumen 106 throughwhich guidewire 101 is slidably disposed, and lumen 107 which exitsthrough a lateral face of catheter 105 at radiused skive 108. Cuttinginstrument 110 is advanced through lumen 107 so that its distal endextends from skive 108 and is substantially transverse to thelongitudinal orientation of catheter 105.

Cutting instrument 110 includes an end effector at its distal end 111which is capable of penetrating the wall of coronary sinus 61 and leftventricle 56 to form passageway 72 therebetween. Cutting instrument maycomprise, for example, a medical laser, as described, for example, inU.S. Pat. No. 5,104,393, which is incorporated herein by reference, or amechanical cutting element, such as a rotating blade (commonly used inatherectomy), or a cannulating needle. As shown in FIG. 8B, once distalend 111 of cutting instrument 110 is advanced into the left ventricle,the cutting instrument is withdrawn from lumen 107 while catheter 105 isretained in place.

Referring now to FIGS. 7 and 8D, guidewire 96 and catheter 90 (carryingstent 71) are advanced through lumen 107 of catheter 105 until guidewire96 enters through passageway 72 into left ventricle 56. Catheter 90 isadvanced along guidewire 96 until it abuts the wall of the coronarysinus. Pusher member 94 is then advanced within exterior sheath 91 sothat spool 93 urges stent 71 out of sheath 91 and, guided by guidewire96, into engagement in passageway 72. When implanted, flange 81 contactsthe interior wall of the coronary sinus while tubular member 80 extendsinto the myocardium of the left ventricle, with barbs or ribs 83anchoring stent 71 in position. Catheter 90, guidewire 96 and catheter105 are then withdrawn from the coronary sinus via the coronary ostium,while guidewire 101 remains in place.

In FIG. 8E, a new catheter 90 loaded with plug 70 is advanced alongguidewire 101 so that the tapered end of plug 70 enters through thecoronary ostium and engages the interior wall of the coronary sinus.Pusher member 94 is again advanced to implant plug 70 into the coronarysinus through the coronary ostium, so that flange 78 of plug 70 contactsthe endocardium of right atrium 53. Guidewire 101 and catheter 90 arethen withdrawn, completing the procedure.

Applicants expect that when implanted in the heart, plug 70 and stent 71will result in long-term retrograde perfusion of the myocardium usingthe cardiac venous system, and will cause a redistribution of flowwithin the venous system so that a greater fraction of the deoxygenatedblood exits via the lymphatic system and the Thebesian veins. Andbecause valve 77 of plug 70 opens when the pressure in the coronarysinus exceeds about 60 mm Hg, it is expected that problems associatedwith edema of the cardiac veins observed in the aforementionedhistorical attempts at coronary venous bypass grafting will be overcome.Applicants further note that while the venous system is not co-extensivewith the coronary arteries (particularly with respect to the rightventricle), it is nevertheless expected that the method and apparatus ofthe present invention will provide relief in the majority of cases,since right ventricular infarcts are less common.

As will be apparent to one of skill in the art of cardiology, the abovedescribed methods may be practiced with other instruments and techniqueswhich are per se known. For example, conventional angiographic methodsmay be employed to map the arterial and venous systems and the anatomyof the left ventricle. In addition, access to the coronary sinus may behad via the femoral veins. Moreover, passageway 72 could be createdbetween the left ventricle and the coronary sinus by advancing thecutting instrument from within the left ventricle (for example, byinsertion through a femoral artery, the aorta, and through the aorticvalve) and into the coronary sinus, after which stent 71 could bedisposed in the passageway with flange 81 engaging the left ventricularendocardium.

Referring now to FIG. 9, an alternative method of creating a venousbypass is described, in which like parts of the heart are labeled withlike reference numerals. In FIG. 9, first end 121 of conduit 120 isplaced in passageway 63 created between right atrium 53 and posteriorseptal endocardium 64 of left ventricle 56, while second end 122 ofconduit 120 extends through coronary ostium 62 and engages the interiorwall of coronary sinus 61.

Conduit 120, shown in FIG. 10, has first end 121, second end 122 andvalved section 123. Conduit 120 may be formed of a flexible andcompliant material, such as silicon tubing, or a suitable syntheticgraft material, for example, a polyester fabric, such as Dacron®, aregistered trademark of E. I. DuPont de Nemours, Wilmington, Del. Thematerial selected for conduit 120 may vary depending upon the intendedmethod of implantation of the conduit. For example, if conduit 120 is tobe implanted surgically, there may be advantages to employing a materialsuch as silicon tubing for the conduit. Alternatively, if conduit 120 isto be implanted transluminally, it may be advantageous to employ amaterial such as a biocompatible fabric that can be compressed to asmaller diameter to pass through a catheter.

First end 121 of conduit 120 has disposed from it tubular member 124similar in construction to stent 71 of FIG. 6. Tubular member 124, whichmay comprise a compliant material as described hereinabove with respectto stent 71, includes proximal flange 125 and a plurality of ribs orbarbs 126 that engage the myocardium and prevent movement of first end121 when it is implanted. Tubular member 124 may optionally includeone-way valve 127 to prevent suction of blood from conduit 120 into theleft ventricle during cardiac diastole.

Second end 122 of conduit 120 includes fitting 128. Fitting 128comprises tubular member 129 having proximal flange 130, a plurality ofoutwardly extending barbs or ribs 131, and tapered distal portion 132.When implanted in the heart, tapered portion 132 of fitting 128 extendsthrough the coronary ostium into the coronary sinus, while flange 130abuts against the right atrial endocardium.

Still referring to FIG. 10, conduit 120 includes valved section 123,which may be disposed between first and second ends 121 and 122 ofconduit 120, so as to not interfere with implantation of either tubularmember 124 or fitting 128. Valved section 123 includes pressuresensitive valve 133 disposed in its lateral wall. Valve 133 serves thesame function in the present embodiment as valve 77 serves in theembodiment of FIG. 5. In particular, valve 133 is constructed to openwhen the pressure in conduit 120 exceeds a predetermined value, forexample, 60 mm Hg.

As will be apparent from the design of conduit 120 and the descriptionhereinabove, conduit 120 provides retroperfusion of the myocardium viathe coronary sinus when implanted. During cardiac systole, blood in theleft ventricle is pushed through tubular member 124, through conduit120, and into coronary sinus 61 via fitting 128. When the pressureexceeds the peak pressure sustainable by the coronary sinus, valve 133opens to vent blood from the left ventricle into the right atrium,thereby preventing further rise in the pressure induced in the coronarysinus. Applicants expect that this aspect of the present invention willprovide improved myocardium perfusion without the problems encounteredin earlier attempts to provide transvenous myocardial perfusion.

Conduit 120 of FIGS. 9 and 10 may be surgically implanted in the heartusing a variation of conventional surgical technique. In particular,following a conventional thorocotomy to expose the heart, an incisionmay be made through the exterior wall of the right atrium. A passagewayis formed between right atrium 53 and the posterior septal endocardium64 of the left ventricle via the posterior pyramidal space using acannulating needle. Tubular member 124 is then implanted in thepassageway. Second end 122 of conduit is implanted in coronary ostium 62so that tapered end 132 extends into the coronary sinus and flange 130abuts against the right atrial endocardium.

Alternatively, conduit 120 may be implanted using a transluminalapproach that is a variation of the Brockenbrough method ofcatheterizing the left ventricle. The conventional Brockenbroughtechnique is described in CARDIAC CATHETERIZATION AND ANGIOGRAPHY, W.Grossman, ed., at pages 63-69, published by Lea & Febiger, Philadelphia(1980), which is incorporated herein by reference. In the conventionalBrockenbrough technique, a catheter and needle combination is advancedthrough the right femoral artery and into the right atrium. The needleis then used to puncture the septum between the right and left atria,after which the catheter is advanced through the mitral valve and intothe left ventricle.

In accordance with the present invention, a Brockenbrough needle kit,available from United States Catheter and Instrument Corp., Billerica,Mass., is advanced over a guidewire into the right atrium via the rightinternal jugular vein using standard Seldinger technique. TheBrockenbrough needle is then advanced through the right atrialendocardium, the posterior pyramidal space, and through the septalendocardium of the left ventricle to form a passageway between the rightatrium and the septal endocardium of the left ventricle. The initialtranseptal puncture made with the Brockenbrough needle is dilated using,for example, progressively larger catheters, which are then withdrawn,leaving the guidewire in place.

Referring now to FIG. 11A, conduit 120 is threaded onto the proximal endof guidewire 140 that is positioned in the transeptal passageway.Conduit 120 is placed on guidewire 140 so that the guidewire enters theconduit through valve 133 and extends through tubular member 124.Conduit 120 is folded over so that second guidewire 141 extends throughvalve 133 and fitting 128. Pusher member 143 is disposed around conduit120 so that it contacts the proximal face of flange 125, the remainderof conduit 120, including fitting 128 and valved section 123, beinginserted within a lumen of pusher member 143. Pusher member 143 andconduit 120 are then loaded into exterior sheath 144. Using thisarrangement, pusher member 143 is disposed to push tubular member 124(and connected conduit 120) in a distal direction along guidewire 140.

Conduit 120, pusher member 143 and exterior sheath are then advancedalong guidewire 140 until the distal end of exterior sheath 144 abutsagainst the right atrial septum adjacent the transeptal passageway.Pusher member 143 is advanced within exterior sheath 144 to drivetubular member 124 into the transeptal passageway. The plurality ofbarbs or ribs 126 thereby engage septal myocardium 73, while the distalface of flange 125 abuts against the right atrial endocardium, as shownin FIG. 11B. Exterior sheath 144 and pusher member 143 are withdrawnalong guidewire 140, leaving the guidewires 140 and 141 in place. Whenpusher member 143 is withdrawn, conduit 120 and fitting 128 aredeployed, with guidewire 141 already extending from the distal end offitting 128. Guidewire 140 is then withdrawn.

Referring now to FIG. 12, catheter 160 having slot 161 in its distal endis employed as will now be described. After deployment of conduit 120and fitting 128 from within pusher member 143, guidewire 141 ismanipulated so that-it enters the coronary sinus through the coronaryostium. Catheter 160 is then advanced along guidewire 141. Slot 161 incatheter 160 is sized to permit conduit 120 to slide within catheter 160through slot 161, so that distal end face 162 abuts directly against theproximal face of flange 130. Once catheter 160 contacts flange 130 offitting 128, catheter 160 is further advanced along guidewire 141 todrive the tapered end of fitting 128 through the coronary ostium andinto engagement with the interior wall of the coronary sinus. Catheter160 and guidewire 141 are then withdrawn, completing the implantation ofconduit 120.

As will of course be apparent to one of skill in the art, other methodsfor transluminally implanting conduit 120 may occur to one of skill inthe art. For example, instead of catheter 160, the grasping teeth of amyocardial biopsy catheter may be used to grasp fitting 128 and steerthe fitting into engagement with the coronary ostium. Additionally, asecond biopsy catheter could be brought into the right atrium via theright femoral artery, if desired, to assist in implantation of either orboth ends of conduit 120.

While preferred illustrative embodiments of the invention are describedabove, it will be obvious to one skilled in the art that various changesand modifications may be made therein without departing from theinvention and the appended claims are intended to cover all such changesand modifications which fall within the true spirit and scope of theinvention.

What is claimed is:
 1. Apparatus for use in treating ischemic heartdisease by providing long-term retrograde transvenous myocardialperfusion, the apparatus comprising:a conduit adapted to be disposedbetween a patient's left ventricle and the patient's coronary sinus, sothat blood flows through the conduit from the left ventricle to thecoronary sinus during cardiac systole; means for partially occluding thepatient's coronary ostium; and a valve for limiting a peak pressureattained within the coronary sinus by venting blood from the conduitinto the patient's right atrium when the pressure attained within thecoronary sinus exceeds a predetermined value.
 2. The apparatus asdefined in claim 1 further comprising:a cutting instrument adapted forinsertion into the coronary sinus via the coronary ostium, the cuttinginstrument boring through a wall of the coronary sinus, through thepatient's epicardium, myocardium and endocardium to create a passagewaybetween the left ventricle and the coronary sinus within which theconduit is implanted.
 3. The apparatus as defined in claim 1 wherein theconduit comprises:a tubular member having a central bore, and exteriorsurface, and a plurality of engagement means located on the exteriorsurface.
 4. The apparatus as defined in claim 3 wherein the tubularmember further comprises a one-way valve that prevents backflow of bloodfrom the coronary sinus to the left ventricle.
 5. The apparatus asdefined in claim 1 wherein the valve is disposed within a bore of themeans for partially occluding the coronary ostium, the valve openingwhen the pressure exceeds the predetermined value.
 6. The apparatus asdefined in claim 1 wherein the conduit comprises:a tubular member havinga first end, a second end, and a lumen extending therebetween, thetubular member comprising a flexible material, the means for partiallyoccluding comprising the second end of the tubular member; means forengaging the first end of the tubular member in a passageway extendingfrom the right atrial endocardium and into the left ventricular septalendocardium; and means for engaging the second end of the device in thecoronary ostium.
 7. The apparatus as defined in claim 6 wherein thefirst and second ends of the conduit are adapted for transluminalimplantation.
 8. The apparatus as defined in claim 6 wherein the meansfor engaging comprises a plurality of ribs or barbs.
 9. The apparatus asdefined in claim 6 wherein the conduit further comprises a one-way valvethat prevents backflow of blood from the coronary sinus to the leftventricle.
 10. The apparatus as defined in claim 6 wherein the valve isdisposed in the conduit.
 11. A kit for use in treating ischemic heartdisease by providing long-term retrograde transvenous myocardialperfusion, the kit comprising:means for forming a passageway havingfirst and second ends, the first end in fluid communication with apatient's left ventricle, the second end in fluid communication with thepatient's coronary sinus, the passageway providing a lumen for bloodflow from the left ventricle to the coronary sinus and extending from aninterior surface of the coronary sinus into the left ventricle, themeans for forming configured for percutaneous, transluminal insertioninto the coronary sinus; a plug adapted to be disposed in the patient'scoronary ostium to partially occlude the coronary ostium.
 12. The kit asdefined in claim 11 wherein the plug further comprises a valve thatlimits a peak pressure attained within the coronary sinus by ventingblood from the coronary sinus into the patient's right atrium when thepressure attained within the coronary sinus exceeds a predeterminedvalue.
 13. The kit as defined in claim 11 further comprising:a deliverysystem adapted for percutaneous insertion into coronary ostium todeliver the plug.
 14. The kit as defined in claim 11 furthercomprising:a tubular member having a central bore, an exterior surface,and a plurality of engagement means located on the exterior surface, thetubular member configured for percutaneous, transluminal insertion inthe passageway so that the plurality of engagement means engage a tissuesurface within the passageway.
 15. The kit as defined in claim 14wherein the plurality of engagement means comprises a plurality of ribsor barbs.
 16. The kit as defined in claim 14 wherein the tubular memberfurther comprises a one-way valve that prevents backflow of blood fromthe coronary sinus to the left ventricle.
 17. Apparatus for use intreating ischemic heart disease by providing long-term retrogradetransvenous myocardial perfusion, the apparatus comprising:a conduithaving first and second ends and an intermediate portion located betweenthe first and second ends, the first end adapted to be disposed in fluidcommunication with a patient's left ventricle, the second end adapted tobe disposed in the coronary ostium in fluid communication with thepatient's coronary sinus, the conduit providing a lumen for blood flowfrom the left ventricle to the coronary sinus during cardiac systole, afirst region of the conduit near the first end adapted to be disposed ina passageway extending between the right atrial endocardium and the leftventricular septal endocardium, the intermediate portion extending intothe right atrium; a valve disposed in the intermediate portion to limita peak pressure attained within the coronary sinus, the valve ventingblood from the coronary sinus into the right atrium when the pressureattained within the coronary sinus exceeds a predetermined value. 18.The apparatus as defined in claim 17 further comprising:a cuttinginstrument adapted for percutaneous insertion into the right atrium tocreate a passageway extending from the right atrial endocardium and intothe left ventricular septal endocardium.
 19. The apparatus as defined inclaim 17 wherein the conduit further comprises:a tubular member formedfrom a flexible material; means for engaging the first region in thepassageway extending between the right atrial endocardium and the leftventricular septal endocardium; and means for engaging the second endwithin the coronary sinus through the coronary ostium.
 20. The apparatusas defined in claim 19 wherein the means for engaging comprises aplurality of ribs or barbs.
 21. The apparatus as defined in claim 17wherein the conduit further comprises a one-way valve disposed withinthe lumen between the first end and the intermediate portion, theone-way valve preventing backflow of blood from the coronary sinus tothe left ventricle.
 22. The apparatus as defined in claim 17 wherein theconduit is adapted for percutaneous implantation.